Tillmanns Angeline R, Pick Frances R, Aranda-Rodriguez Rocio
Center for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada.
Environ Toxicol. 2007 Apr;22(2):132-43. doi: 10.1002/tox.20250.
Microcystins (MC), a group of cyanotoxins, have been found in lakes and rivers worldwide. One goal of MC research is to develop models which predict MC concentrations, but these efforts have been hampered by a lack of standardized methods necessary for comparing data across studies. Here, we investigate the effect of chemical analysis (HPLC-PDA and ELISA), sample collection (whole water, plankton tow and surface scum), and choice of normalizing parameter (volume, dry weight, and chlorophyll a) on reported MC concentrations. Samples were collected over three years from a temperate mesotrophic, shallow lake with episodic blooms of cyanobacteria. We found that microcystins were up to four times higher in lake samples when analyzed by ELISA relative to HPLC-PDA and that MC concentration measured by HPLC explained less than half of the variation in MC concentrations measured by ELISA. Also, samples collected by plankton tow gave consistently higher concentrations than whole water samples. An additional HPLC analysis of two chlorophyte cultures revealed the presence of compounds with a similar UV absorbance spectrum to MC-LR, suggesting that identifying MC based solely on UV absorbance is not valid. Our results document the discrepancy in MC concentrations that can arise by using different methods throughout all stages of sampling, analysis, and reporting of MC concentrations.
微囊藻毒素（MC）是一类蓝藻毒素，已在世界各地的湖泊和河流中被发现。MC研究的一个目标是开发能够预测MC浓度的模型，但这些努力因缺乏跨研究比较数据所需的标准化方法而受阻。在此，我们研究了化学分析方法（高效液相色谱-光电二极管阵列检测法和酶联免疫吸附测定法）、样本采集方式（全水样、浮游生物拖网样和表面浮沫样）以及归一化参数选择（体积、干重和叶绿素a）对所报告的MC浓度的影响。在三年时间里，从一个有蓝藻水华爆发的温带中营养浅湖采集样本。我们发现，相对于高效液相色谱-光电二极管阵列检测法，酶联免疫吸附测定法分析的湖泊样本中微囊藻毒素含量高出四倍，并且高效液相色谱法测得的MC浓度解释的酶联免疫吸附测定法测得的MC浓度变化不到一半。此外，浮游生物拖网采集的样本浓度始终高于全水样。对两种绿藻培养物进行的额外高效液相色谱分析显示，存在与MC-LR具有相似紫外吸收光谱的化合物，这表明仅基于紫外吸收来鉴定MC是无效的。我们的结果证明了在MC浓度的采样、分析和报告的所有阶段使用不同方法可能导致的MC浓度差异。
